Compositions for the inhibition of giardia lamblia

ABSTRACT

The present invention relates to a composition exhibiting a bile-salt hydrolase activity for its use for the treatment or the prevention of giardiasis, said composition comprising a bile-salt hydrolase (BSH) enzyme, a bacterium able to secrete a BSH, a recombinant host cell able to secrete a BSH, or a combination thereof. The present invention also relates to the use of a composition exhibiting a BSH activity for the treatment or the prevention of giardiasis, and to a pharmaceutical composition or a food composition comprising, as an active principle, a BSH, a lactic acid bacterium able to secrete a BSH, or a recombinant host cell able to secrete a BSH.

The present invention relates to a composition exhibiting a bile-salthydrolase activity for its use for the treatment or the prevention ofgiardiasis, said composition comprising a bile-salt hydrolase (BSH)enzyme, a bacterium able to secrete a BSH, a recombinant host cell ableto secrete a BSH, or a combination thereof. The present invention alsorelates to the use of a composition exhibiting a BSH activity for thetreatment or the prevention of giardiasis, and to a pharmaceuticalcomposition or a food composition comprising, as an active principle, aBSH, a bacterium able to secrete a BSH, or a recombinant host cell ableto secrete a BSH.

Giardia lamblia is a parasitic protozoan responsible for giardiasis, adisease characterized by acute or chronic intestinal malabsorption,diarrhea, weight loss, dehydration and abdominal pain in humans and avariety of animals. It is one of the most common intestinal parasites inthe world. Giardiasis has high veterinary impact and high impact onpublic health, is responsible for important human morbidity, especiallycausing nutritional deficiencies in children in developing countries(Ali and Hill, 2003). Developed countries are also concerned bygiardiasis and outbreaks have been associated with drinking watercontamination resulting from runoff of contaminated soils by rain falls,agricultural practices and sewage treatment plant dysfunctions (Mons etal., 2009).

G. lamblia enters vertebrates when cysts are ingested with food, wateror fomites contaminated by feces from infected hosts. Cysts remaininfective for months in environmental waters. They are highly resistantto chlorinated disinfectants used in drinking water treatments andinfectious doses are low (10 to 100 cysts). After ingestion, infectiveforms excyst, releasing trophozoites that establish infections in theupper small intestine (duodenum) where they interact with the intestinalbarrier. Duodenum is a very specific environment where food from thestomach, bile from the gall bladder and digestive enzymes from thepancreas pour in. There, G. lamblia divides by binary fission andeventually exits the host with the feces once trophozoites havere-formed cysts. The drug of choice for treating giardiasis remainsmetronidazole, a 5-nitroimidazole, which is reduced into toxic compoundsby the parasite enzyme pyruvate:ferredoxin oxido-reductase. Side effectsof drug treatment are reported and metronidazole resistance appears invitro and in clinical settings (up to 20% of environmental strains werereported as resistant) (Uperoft and Uperoft, 2001).

How Giardia pathology is produced is still unclear but it is probablymultifactorial (Farthing et al., 1997). Patho-physiologies observedcomprise damages of the host mucosal surface by microvillus and cryptatrophy, decreased epithelial permeability and impairment of theactivity of digestive enzymes. These changes may be due as much tofactors of the host as to those of the parasite.

It is now widely recognized that intestine microbiota plays a role inthe protection of the host against gut colonization by pathogens(Travers et al., 2011). Different mechanisms may be responsible for theprotective effects: competition for pathogen receptor sites, barrier forpathogen access, production of antimicrobial compounds, competition fornutritional substrates and enhancement of the innate and adaptive hostimmune responses (Tancrede et al., 1992). Nutritional strategies arebased on an increase of the components of the gut microbiota that areassociated with the protective activity (Brassard D. and Schiffrin E J.,1997). Colonization of the intestine by G. lamblia strongly depends onthe gut microbiota (Singer and Nash, 2000). Evidences strongly suggestthe involvement of the bacterium Enterococcus faecium in the host immuneresponse against G. lamblia (Benyacoub et al., 2005). Extracellularfactors of L. johnsonii La1 block the in vitro growth of G. lamblia inG1 phase indicating that bacteria may directly affect parasitedevelopment (Perez et al., 2001). It was shown that the probioticbacteria Lactobacillus johnsonii La1 antagonizes G. lambliaestablishment in rodent model (Humen et al., 2005).

The increasing numbers of outbreaks of giardiasis due to drinking watercontamination, the side effects of available anti-Giardia drugs as wellas, the increasing emergence of resistance to these drugs, rendergiardiasis a worrying subject, and there is a real need for alternativetherapeutic strategies.

The present invention now provides compositions exhibiting a bile-salthydrolase (BSH) activity as effective inhibitors for Giardia lamblia,for the prevention or the treatment of giardiasis. The inventors haveindeed shown that parasite growth inhibition is mediated by secretedbacteria bile-salt hydrolase activity(ies) that produce(s) deconjugatedbile salts from bile present in the culture medium, and that, unlikenormal conjugated bile salts which are the main components of the bile,deconjugated bile salts are found toxic for Giardia.

Anti-Giardia activity was studied in vivo and in vitro for L. johnsoniiLa1 (LjLa1) (Perez et al. 2001, Humen et al. 2005). The genomes of L.johnsonii La1 and G. lamblia were sequenced (Pridmore et al. 2004,Morrison et al. 2007). Halliday et al (1995) disclose that G. lambliainternalizes conjugated bile salts, however this document does notmention a role for unconjugated bile salts. Shukla et al. (2011, 2012,2013) describe that the administration of Lactobacillus rhamnosuslessens the severity of giardiasis. U.S. Pat. No. 6,905,679 discloses amethod for the treatment of a disorder associated with the colonizationof gut by Giardia intestinalis comprising the administration ofLactobacillus acidophilus La10 bacteria (CNCM reference number 1-2332),of Bifidobacterium bifidum (1-2333) or of Bifidobacterium infantis(1-2334). The inhibitory effect of lactic acid bacteria is possiblyattributed to particular organic acids secreted by said lactic acidbacteria.

However, none of these documents disclose the role of bile-salthydrolase activity, in the presence of bile salts, for the inhibition ofGiardia lamblia.

A composition according to the present invention represents a newtherapeutic strategy against Giardia lamblia, based on the naturalcatalytic activity of bile-salt hydrolases, in order to prevent or treatgiardiasis. A composition according to the invention furthermorerepresents a public health interest by providing a means to counteractthe emergence of drug resistant Giardia strains.

The invention will become more fully understood from the detaileddescription given herein and from the accompanying drawings, which aregiven by way of illustration only and do not limit the intended scope ofthe invention.

The present invention first relates to a composition exhibiting abile-salt hydrolase activity for the treatment or the prevention ofgiardiasis.

The term “bile-salt hydrolase activity” or “BSH activity” refers to theability of a composition according to the invention to hydrolyseconjugated bile-salts to generate deconjugated bile salts, and glycineor taurine. BSH cleave the peptide linkage of bile acids, which resultsin removal of the amino acid group from the steroid core and in theproduction of deconjugated, or unconjugated, bile acids, whichprecipitate at low pH.

The expression “treatment or prevention of giardiasis” refers to thetreatment or the prevention of disorders associated with the presence inthe gut of Giardia lamblia or of Giardia intestinalis, and in particulardisorders associated with the infestation and/or colonization of the gutby said parasites.

Conjugated bile salts, or bile acids, are glycocholic acid (GCA),taurocholic acid (TCA), glycodeoxycholic acid (GDCA), taurodeoxycholicacid (TDCA), glycochenodeoxycholic acid (GCDCA) andtaurochenodeoxycholic acid (TCDCA). Unconjugated bile-salts, also calleddeconjugated bile salts are: cholic acid (CA), deoxycholic acid (DCA)and chenodeoxycholic acid (CDCA).

BSH activity is assessed by the detection the products generated by theenzymatic reaction, in particular the detection:

-   -   of glycine and/or taurine, liberated from conjugated bile salts,    -   of cholic acid (CA), deoxycholic acid (DCA) and/or        chenodeoxycholic acid (CDCA)        by classical detection methods well known by a person skilled in        the art of enzymology, including, without restriction,        chromatography, mass-spectrometry, proteomic analysis,        spectrophotometry, fluorometry, colorimetry or        chemiluminescence, and any method such as described in the        present specification. In a particular embodiment, CA, DCA        and/or CDCA are detected by mass spectrometry analysis        (LC/ESI-MS analysis) of bile components, and proteomic analysis.

A specific method for detection of BSH activity includes a method suchas described in the present specification, using mass spectrometryanalysis (LC/ESI-MS analysis) and proteomic analysis of bile components.It may also be detected, in bacteria, by a method comprising the growthof said bacteria in an adapted broth, the streaking of bacteria ontomedium supplemented, or not, with 0.2% (wt/vol) glycodeoxycholic acidand anaerobic incubation for 48 h. The white precipitates aroundcolonies and the clearing of the medium are indicative of BSH activity.

Therefore, the present invention relates to a composition exhibiting abile-salt hydrolase activity for the treatment or the prevention ofgiardiasis, said composition comprising at least one of the followingelements, or a combination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus La10        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        1-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH.

The present invention also relates to a composition exhibiting abile-salt hydrolase activity for the treatment or the prevention ofgiardiasis, said composition comprising at least one of the followingelements, or a combination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        I-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH,        wherein said BSH activity is determined by the detection of the        presence of glycine or taurine, liberated from conjugated bile        salts, or by the detection of the presence of cholic acid (CA),        deoxycholic acid (DCA), and/or chenodeoxycholic acid (CDCA).

The BSH activity of a BSH enzyme is expressed as enzymatic units (U)when tested using a taurodeoxycholic and/or a glycodeoxycholicsubstrate. An example of this determination is described in Example 13of the present patent application. The level of the activity of a BSH,in a composition according to the invention, can be expressed byreference to the activity of commercial C. perfringens BSH, and possiblyusing a test for said activity as described in the C. perfringensmanufacturer's notice.

In a particular embodiment, the present invention relates to acomposition exhibiting a BSH activity for use for the treatment orprevention of giardiasis, wherein said BSH activity is comprised between0.0001 U and 100 U, between 0.001 U and 10 U, between 0.01 U and 1 U,between 0.1 U and 0.5 U.

In a first particular embodiment, the present invention relates to acomposition exhibiting a bile-salt hydrolase activity for the treatmentor the prevention of giardiasis, wherein the bile-salt hydrolaseactivity is associated with the presence of at least one bile-salthydrolase (BSH) enzyme.

In another particular embodiment, the present invention relates to acomposition exhibiting a BSH activity for use for the treatment orprevention of giardiasis, wherein said composition comprises a BSHenzyme, or is a able to secrete at least one BSH enzyme, wherein theconcentration of BSH present in said composition is comprised between0.01 μg/ml and 10 mg/ml, between 0.1 μg/ml and 1 mg/ml, between 0.5μg/ml and 200 μg/ml, between, between 1 μg/ml and 100 μg/ml, between 1μg/ml and 50 μg/ml or between 5 μg/ml and 20 μg/ml. In a more particularembodiment, a composition according to the invention exhibits abile-salt hydrolase activity associated with the presence of at leastone bile-salt hydrolase (BSH) enzyme, said enzyme being chosen amongprokaryotic BSH, or BSH synthesized by bacteria. In a more particularembodiment, a composition according to the invention exhibits abile-salt hydrolase activity associated with the presence of at leastone bile-salt hydrolase (BSH) enzyme synthetized by a lactic acidbacterium.

A lactic acid bacterium is defined as gram positive bacteria sharingcommon metabolic and physiological characters, wherein lactic acid isproduced as a major metabolic end product of carbohydrate fermentation.The group of lactic acid bacteria includes in particular Lactobacillus,Lactococcus and Bifidobacterium. In a more particular embodiment, acomposition according to the invention exhibits a bile-salt hydrolaseactivity associated with the presence of at least one bile-salthydrolase (BSH) enzyme which amino acid sequence comprises an amino acidsequence having at least 80% identity, at least 85%, at least 90%, atleast 95%, at least 98% or at least 99% identity with, or which is anatural variant of, an amino acid sequence chosen in the groupconsisting of:

-   -   Lactobacillus johnsonii La1 BSH-12 (LJ 1412) (SEQ ID No 1,        UniProtKB entry number Q74IV4)    -   Lactobacillus johnsonii La1 BSH-47 (LJ 1147) (SEQ ID No 2,        UniProtKB entry number Q74JG0)    -   Lactobacillus johnsonii La1 BSH-56 (LJ 0056) (SEQ ID No 3,        UniProtKB entry number Q74LX7)    -   Lactobacillus gasseri (ATCC reference: 33323) BSH-A (SEQ ID No        4, UniProtKB entry number B9V405)    -   Lactobacillus gasseri BSH-B (SEQ ID No 5, UniProtKB entry number        Q9AHJ7)    -   Lactobacillus johnsonii DPC 6026 (SEQ ID No 6, UniProtKB entry        number F4AE15),    -   Lactobacillus johnsonii DPC 6026 (SEQ ID No 7, UniProtKB entry        number F4ACA3),    -   Lactobacillus johnsonii DPC 6026 (SEQ ID No 8, UniProtKB entry        number F4ADE7).

Any BSH enzyme suitable in a composition according to the presentinvention is easily found by a man skilled in the art, and may bechosen, in particular, among the following:

-   -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4AE15,    -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4ACA3,    -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4ADE7,    -   Lactobacillus johnsonii pf01 BSH, UniProtKB entry number F7SHH3,        and    -   Lactobacillus johnsonii pf01 BSH, UniProtKB entry number F7SGA1.

The present invention comprises the presence of variants of BSH enzymeshaving at least 80%, at least 85%, preferably 90%, at least 90%, morepreferably 95%, at least 95% and even more preferably 98%, at least 98%or at least 99% identity with a sequence chosen in the group consistingof SEQ ID No 1 to SEQ ID No 7. As used herein the term “identity” hereinmeans that two amino acid sequences are identical (i.e. at the aminoacid by amino acid) over the window of comparison. The term “percentageof sequence identity” is calculated by comparing two optimally alignedsequences over the window of comparison, determining the number ofpositions at which the identical amino acid residues occurs in bothsequences to yield the number of matched positions, dividing the numberof matched positions by the total number of positions in the window ofcomparison (i.e. the window size) and multiplying the result by 100 toyield the percentage of sequence identity. The percentage of sequenceidentity of an amino acid sequence can also be calculated using BLASTsoftware with the default or user defined parameter. As applied topolypeptides, the term substantial identity means that two peptidesequences, when optimally aligned, share at least about 80% sequenceidentity, preferably at least 85% identity, preferably at least about90% sequence identity, more preferably at least about 95% sequenceidentity, at least 98% sequence identity or more (e.g., 99% sequenceidentity). As used herein, a “derivative” or “sequence derived from”, or“natural variant” refers to an amino acid sequence having at least 80%identity, preferably at least 85% identity, more preferably at least 90%identity and even more preferably at least 95% identity or more, such asat least 98% sequence identity or 99% identity with said reference aminoacid sequence.

More particularly, the present invention refers to a compositionexhibiting a bile-salt hydrolase activity associated with a BSH enzyme,for its use in the prevention of the treatment of giardiasis, whereinthe amino acid sequence of said enzyme is chosen among the following:

-   -   Lactobacillus johnsonii La1 BSH-12 (SEQ ID No 1),    -   Lactobacillus johnsonii La1 BSH-47 (SEQ ID No 2),    -   Lactobacillus johnsonii La1 BSH-56 (SEQ ID No 3),    -   Lactobacillus gasseri BSH-A (SEQ ID No 4),    -   Lactobacillus gasseri BSH-B (SEQ ID No 5),    -   Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 6), UniProtKB        entry number F4AE15,    -   Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 7), UniProtKB        entry number F4ACA3,    -   Lactobacillus johnsonii DPC 6026 BSH (SEQ ID No 8). UniProtKB        entry number F4ADE7

In another particular embodiment, the invention relates to a compositionexhibiting a bile-salt hydrolase activity for its use in the preventionof the treatment of giardiasis, wherein said composition comprises alactic acid bacteria able to secrete a BSH, said lactic acid bacteriabeing chosen among: Lactococcus, Lactobacillus, with the exception ofthe bacterial strains Lactobacillus johnsonii La1 (NCC533, CNCM 1-1225)and of Lactobacillus acidophilus (NCC90, CNCM 1-2332), andBifidobacterium, with the exception of the bacterial strainsBifidobacterium bifidum (NCC189, CNCM 1-2333) and of Bifidobacteriuminfantis (NCC200, CNCM 1-2334).

The term “lactic acid bacteria” refers to the presence of at least onemicro-organism, wherein the micro-organism is preferably present ofabout 106 to 1012 cfu (colony forming unit). The microorganisms may bepresent as such or optionally after a step of purification from aculture medium. In another embodiment, a composition according to theinvention comprises the supernatant of a culture medium of saidmicroorganism, which may be concentrated by any method known by a manskilled in the art.

Therefore, the invention relates to a composition exhibiting a bile-salthydrolase activity for its use in the prevention of the treatment ofgiardiasis, said composition comprising a Lactobacillus, with theexception of the bacterial strains Lactobacillus johnsonii La1 (NCC533,CNCM 1-1225) and of Lactobacillus acidophilus (NCC90, CNCM 1-2332).

The invention also relates to a composition exhibiting a bile-salthydrolase activity for its use in the prevention of the treatment ofgiardiasis, said composition comprising a Bifidobacterium, with theexception of the bacterial strains Bifidobacterium bifidum (NCC189, CNCM1-2333) and of Bifidobacterium infantis (NCC200, CNCM 1-2334).

In a more particular aspect, a composition according to the inventioncomprises a Lactobacillus chosen in the group consisting of:

-   -   Lactobacillus johnsonii, with the exception of the bacterial        strains Lactobacillus johnsonii La1 (NCC533, CNCM 1-1225)    -   Lactobacillus gasseri,    -   Lactobacillus acidophilus, with the exception of Lactobacillus        acidophilus (NCC90, CNCM 1-2332), and    -   Lactobacillus reuteri.

The following bacterial strains have shown a particular activity in acomposition according to the invention, as shown in the “Examples” partof the specification.

In a particular embodiment, the invention relates to a compositionexhibiting a bile-salt hydrolase activity for its use in the preventionof the treatment of giardiasis, said composition comprising alactobacillus chosen in the group consisting of the bacterial strainsreferenced as:

-   -   Lactobacillus johnsonii:    -   Bacterial strain deposited at the CNCM, Institut Pasteur, Paris,        under the number I-4885, on Aug. 7, 2014    -   Bacterial strain deposited under the reference CIP103614,    -   Bacterial strain deposited under the reference CIP 103786,    -   Bacterial strain deposited under the reference CIP 103620,    -   Bacterial strain deposited under the reference CIP103652,    -   Bacterial strain deposited under the reference CIP103653,    -   Bacterial strain deposited under the reference CIP103654,    -   Bacterial strain deposited under the reference CIP103781,    -   Bacterial strain deposited under the reference CIP103782,    -   Lactobacillus gasseri:    -   Bacterial strain deposited under the reference ATCC33353,    -   Bacterial strain deposited at the CNCM, Institut Pasteur, Paris,        under the number I-4884, on Aug. 7, 2014,    -   Bacterial strain deposited under the reference LMG11413,    -   Lactobacillus acidophilus    -   Bacterial strain deposited under the reference ATCC700396.

In a particular embodiment, the present invention relates to acomposition exhibiting a BSH activity for the prevention or thetreatment of giardiasis, said composition comprising a lactic acidbacteria able to secrete a BSH, wherein said bacteria are present in anamount comprised between 10⁶ to 10¹² cfu/g of bacteria.

In another particular embodiment, the present invention relates to acomposition exhibiting a bile-salt hydrolase activity for its use in theprevention of the treatment of giardiasis, said composition comprising ahost cell comprising a heterologous nucleic acid sequence encoding forat least one bile-salt hydrolase enzyme, said host cell being able tosecrete said bile-salt hydrolase enzyme.

The term “host cell” refers to a living cell able to receiveheterologous nucleic acid, and able to synthesize at least one proteinencoded by said heterologous nucleic acid. In a preferred embodiment,said heterologous nucleic acid is an expression vector containingnucleic acid sequences able to encode a protein of interest and allnecessary regulatory elements for the production of said protein in saidhost cell.

In a more particular embodiment, a composition according to theinvention comprises a host cell comprising at least one nucleic acidsequence chosen among the following:

-   -   nucleotide sequence encoding for L. johnsonii La1 BSH-12 (SEQ ID        No 9), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 9,    -   nucleotide sequence encoding for L. johnsonii La1 BSH-47 (SEQ ID        No 10), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 10,    -   nucleotide sequence encoding for L. johnsonii La1 BSH-56 (SEQ ID        No 11), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 11.

In another particular embodiment, the invention relates to a host cellfor use in the treatment or the prevention of giardiasis, said host cellcomprising at least one nucleic acid sequence, wherein said at least onenucleic acid sequence may be heterologous, chosen among the following:

-   -   nucleotide sequence encoding for L. johnsonii La1 BSH-12 (SEQ ID        No 9), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 9,    -   nucleotide sequence encoding for L. johnsonii La1 BSH-47 (SEQ ID        No 10), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 10,    -   nucleotide sequence encoding for L. johnsonii La1 BSH-56 (SEQ ID        No 11), or a natural variant thereof, wherein said natural        variant has a nucleotide sequence of at least 80%, at least 85%,        at least 90%, at least 95%, at least 98%, or at least 99%        identity with SEQ ID No 11.

Any BSH enzyme suitable in a composition according to the presentinvention can be selected by a man skilled in the art, and a nucleotidesequence encoding for said enzyme can be found in public databases, itmay be chosen, in particular, among the following:

-   -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4AE15,    -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4ACA3,    -   Lactobacillus johnsonii DPC 6026 BSH, UniProtKB entry number        F4ADE7,    -   Lactobacillus johnsonii pf01 BSH, UniProtKB entry number F7SHH3,    -   Lactobacillus johnsonii pf01 BSH, UniProtKB entry number F7SGA1,    -   Clostridium perfringens BSH    -   Lactobacillus acidophilus BSH, bacterial strain referenced as        ATCC700396.

In a more particular embodiment, a composition according to the presentinvention comprises a host cell comprising at least one nucleic acidsequence encoding for a BSH, said host cell being chosen in the group oflactic acid bacteria. More particularly, said lactic acid bacterium ischosen among lactobacilli and lactococci. In a particular embodiment ofthe invention, said lactic acid bacterium is Lactococcus lactis. Inanother particular embodiment of the invention, said lactic acidbacterium is a lactobacilli chosen among the group consisting of:

-   -   Lactobacillus johnsonii,    -   Lactobacillus reuteri, and    -   L Lactobacillus gasseri.

In another aspect, the present invention relates to the use of acomposition exhibiting a bile-salt hydrolase activity for the treatmentor the prevention of giardiasis, wherein said composition comprises:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacteria able to secrete at least one BSH, with the exception        of the strain Lactobacillus johnsonii La1, Lactobacillus        acidophilus, Bifidobacterium bifidum and Bifidobacterium        infantis,    -   A recombinant host cell able to secrete at least one        heterologous BSH, or    -   A combination thereof.

In a more particular embodiment, the present invention relates to theuse of a composition exhibiting a bile-salt hydrolase activity whereinsaid composition comprises: a bile-salt hydrolase (BSH) enzyme, abacteria able to secrete at least one BSH, with the exception of thestrain Lactobacillus johnsonii La1, Lactobacillus acidophilus,Bifidobacterium bifidum and Bifidobacterium infantis, a recombinant hostcell able to secrete at least one heterologous BSH, or a combinationthereof for the treatment or the prevention of giardiasis, in humanbeings.

In another more particular embodiment, the present invention relates tothe use of a composition exhibiting a bile-salt hydrolase activitywherein said composition comprises: a bile-salt hydrolase (BSH) enzyme,a bacteria able to secrete at least one BSH, with the exception of thestrain Lactobacillus johnsonii La1, a recombinant host cell able tosecrete at least one heterologous BSH, or a combination thereof for thetreatment or the prevention of giardiasis in animals. Indeed, acomposition according to the invention may be used for the treatment orthe prevention of giardiasis in pigs and in cows, therefore, in aparticular embodiment, a composition according to the invention is foruse in the treatment or prevention of giardiasis in pigs or in cows.

In a further aspect, the present invention relates to a pharmaceuticalcomposition comprising, as an active principle, a BSH, a lactic acidbacteria able to secrete at least a BSH, a host cell able to secrete aBSH, or a combination thereof, and a pharmaceutically acceptablecarrier.

A pharmaceutical composition according to the invention comprises aneffective amount of a BSH, a lactic acid bacteria able to secrete atleast a BSH, a host cell able to secrete a BSH, or a combinationthereof, and a pharmaceutically acceptable carrier, wherein saideffective amount is defined as catalytic units (U), for BSH enzyme orrecombinant BSH enzyme, or as a number of colony forming units (cfu),for living bacteria.

A pharmaceutical composition according to the invention is selected froman orally administrable composition, including, with no restriction,tablets, liquid bacterial suspension, dried oral supplement, wet oralsupplement and tube feeding compositions.

Other pharmaceutical or nutritional preparations suitable for oraladministration are hard or soft gelatin capsules made from gelatin and aplasticizer such as glycerol or sorbitol. Hard capsules may include theinventive compound in admixture with fillers such as lactose, binderssuch as starches, and/or lubricants such as talc or magnesium stearate,and if desired, stabilizers. In soft capsules, the inventive compound ispreferably dissolved or suspended in a suitable liquid, such as fattyoil, paraffin oil or a liquid polyethylene glycol, to which a stabilizercan be added.

In a particular embodiment, a pharmaceutical composition according tothe invention comprises an effective amount of a BSH enzyme and apharmaceutically acceptable carrier for an administration to animals. Ina more particular embodiment, a pharmaceutical composition from theinvention comprises a BSH-12, a BSH-47 and/or a BSH-56 enzyme, and acarrier comprising a vehicle for oral administration of molecules, mixedwith a cell culture buffer.

A person skilled in the art is able to choose an adapted vehicle, as anexample, the SYRSPEND® can be cited, and to prepare and adapted mixturefor its oral administration, for example by mixing said vehicle with adiluting solution and/or with a buffer. As an example, a pharmaceuticalcomposition according to the invention comprises an effective amount ofBSH-12, a BSH-47 and/or a BSH-56 enzyme and a carrier comprising amixture of SYRSPEND® NaHCO3 16.4%, DMEM (Dilbecco Modified CultureMedium).

Coated tablet cores can be provided with suitable coatings, which ifappropriate are resistant to gastric juices, using, inter alia,concentrated sugar solutions which may contain gum arabic, talc,polyvinylpyrrolidone, polyethylene glycol and/or titanium dioxide,shellac solutions in suitable organic solvents or solvent mixtures or,for the preparation of coatings resistant to gastric juices, solutionsof suitable cellulose preparations such as acetylcellulose phthalate orhydroxypropylmethylcellulose phthalate. Dyes or pigments can be added tothe tablets or coated tablets, for example, to identify or indicatedifferent doses of the active compound ingredient.

In a more particular embodiment, the present invention relates to apharmaceutical composition comprising a BSH, a lactic acid bacteriumable to secrete at least a BSH, a host cell able to secrete a BSH, or acombination thereof as an active principle, wherein said activeprinciple is encapsulated.

In another particular embodiment, the present invention relates to aprocess for the preparation of a composition exhibiting a bile-salthydrolase activity for the treatment or the prevention of giardiasis,said composition comprising a carrier and at least one of the followingelements, or a combination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus La10        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        1-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH.

In a more particular embodiment, the present invention relates to aprocess for the preparation of a composition exhibiting a bile-salthydrolase activity for the treatment or the prevention of giardiasis,said composition comprising a pharmaceutically acceptable carrier and atleast one of the following elements, or a combination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus La10        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        1-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH.

In another more particular embodiment, the present invention relates toa process for the preparation of a composition exhibiting a bile-salthydrolase activity for the treatment or the prevention of giardiasis,said composition comprising a carrier acceptable for a food compositionor a dietary supplement and at least one of the following elements, or acombination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus La10        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        1-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH.

A process according to the invention comprises at least a step ofcontacting said carrier with an effective amount of said enzyme and/orsaid bacterium and/or said host/cell, wherein said and a step of mixingsaid elements in order to prepare a composition suitable for itsintended use.

The present invention also relates to a method for the prevention or forthe treatment of giardiasis, said method comprising the administration,to a patient in need thereof, of a composition comprising at least oneof the following elements, or a combination thereof:

-   -   A bile-salt hydrolase (BSH) enzyme,    -   A bacterium able to secrete at least one BSH, with the exception        of the bacterial strains Lactobacillus johnsonii La1 (public        reference NCC533, CNCM 1-1225), Lactobacillus acidophilus        (NCC90, CNCM 1-2332), Bifidobacterium bifidum (NCC189, CNCM        I-2333) and Bifidobacterium infantis (NCC200, CNCM 1-2334),    -   A recombinant host cell able to secrete at least one BSH,

In a further aspect, the present invention relates to a food compositionor a dietary supplement comprising, as an active principle, a BSH, alactic acid bacterium able to secrete at least a BSH, a host cell ableto secrete a BSH, or a combination thereof, and optionally a carrier.

A food composition or a dietary supplement according to the inventioncomprise an effective amount of a BSH, a lactic acid bacteria able tosecrete at least a BSH, a host cell able to secrete a BSH, or acombination thereof, and a pharmaceutically acceptable carrier, whereinsaid effective amount is defined as catalytic units (U), for BSH enzymeor recombinant BSH enzyme, or as a number of colony forming units (cfu),for living bacteria.

A food composition or a dietary supplement according to the inventionmay be provided as a dry or a wet composition, and may be selected, withno restriction, among milk, yogurt, cheese, milk powder and pet food.

LEGENDS OF THE FIGURES

FIGS. 1A and 1B: inhibitory effect of LjLa1 supernatant on G. lamblia.FIG. 1A represents parasites concentration as a function of incubationtime in the presence of KM-FCS with (filled symbols) or without (opensymbols) bovine bile (0.75 g/L, final concentration), in presence(squares) or absence (diamonds) of bacterial supernatant (LjLa1sn). Theparasite concentration was estimated by counting lived cells with aMalassez cell chamber, as indicated in example 1. N=2. FIG. 1Brepresents the percentage of G. lamblia growth inhibition after 24 h ofculture is expressed as a function of bile salts concentration (greyhistograms) or of complete bovine bile (black histograms, right part ofthe figure). G. lamblia trophozoites in KM-FCS were incubated for 24 hat 37° C. in anaerobic conditions with LjLA1sn and variousconcentrations of bile salts (0.016, 0.032, 0.048 g/L, finalconcentration) or complete bovine bile (0.5, 0.6, 0.75 g/L, finalconcentration). Growth inhibition values (%) were normalized accordingto control in lactic acid-acidified KM-FCS supplemented with similarconcentrations of bovine bile or bile salts. Number of independentexperiments=3.

FIGS. 2A to 2C: percentage of G. lamblia growth inhibition after 24 h ofculture. FIG. 2A represents the percentage of G. lamblia in the presenceof (from left to right) LjLa1sn with no protease treatment, LjLa1sn withproteinase K, LjLa1sn with pronase; LjLa1sn with catalase or heated at90° C. for 10 min before G. lamblia growth inhibition assay. Growthinhibition (%) was normalized according to matched control: lacticacid-adjusted MTYI medium incubated with protease-coupled beads ortreated for 10 min at 90° C. Number of independent experiments=3. FIG.2B represents the percentage of G. lamblia growth inhibition after 24 hof culture in varying pH. Supernatant from LjLa1 in MTYI medium wasadjusted to pH 6.2, 6.7, 6.9 or 7.2 (histograms from left to right)before Giardia growth inhibition assays. Growth inhibition (%) wasnormalized according to control, i.e. lactic acid-adjusted MTYIsubsequently raised to pH 6.2, 6.7, 6.9 or 7.2. Number of independentexperiments=3. FIG. 2C represents the percentage of G. lamblia growthinhibition after 24 h of culture in supernatant from a culture of LjLa1in KM-FCS medium filtrated through a 10 kDa, 30 kDa or 50 kDa MW cut-offmembrane (from left to right). Acidified KM-FCS alone was processedsimilarly. Fractions above and under respective thresholds were assayedfor Giardia growth inhibition in presence of bile (0.5 g/L). Inhibitionvalues (%) were normalized according to KM-FCS controls. Number ofindependent experiments=3.

FIGS. 3A to 3C: impact of LjLa1 supernatant on bovine bile composition,as shown by total ion chromatograms detected by LC-MS of the SPE-treatedsamples corresponding to an incubation of the bile for 24 h at 37° C.with either KM medium alone (FIG. 3A), LjLa1 supernatant (FIG. 3B) orheat-treated LjLa1 supernatant (FIG. 3C). Metabolic profiles wereestablished, from which the main components were identified using Metlin(Smith et al., 2006) or LMSD (Sud et al., 2007) databases, or from theirMS/MS fragmentation pattern. TC: taurocholate, GC glycocholate, TCDC:taurochenodesoxycholate, TDC: taurodesoxycholate, GCDC:glycochenodesoxycholate, GDC: glycodesoxycholate, C: cholate, CDC:chenodesoxycholate, DC: desoxycholate.

FIGS. 4A and 4B: Increase of non-conjugated salts cholate anddeoxycholate content after treatment of bile with LjLa1 supernatant.FIGS. 4A and 4B represent boxplot showing the relative intensity ofcholate (C) and desoxycholate (DC) for the bile incubated in the absence(left) presence (right) of LjLa1 supernatant.

FIGS. 5A to 5C: G. lamblia growth inhibitory activity and BSH activityco-eluate in the same fractions after separation of LjLa1 supernatant bygel filtration chromatography. FIG. 5A: Chromatography profile. FIG. 5B:BSH activity measured after 24 h of incubation of GDC (2.4 g/l) with gelfiltration fraction collected. FIG. 5C: G. lamblia growth inhibitoryactivity after 24 h of incubation with gel filtration chromatographyfractions in presence of GDC (0.2 g/l).

FIG. 6: Inhibition of Giardia lamblia growth by enzymatically active C.perfringens BSH in the presence of glycine—(GDC, GCDC) or taurine—(TDC,TCDC) conjugated bile salts. Commercial C. perfringens BSH,enzymatically active (dark bars) or inactivated (light bars) by aheat-treatment (100° C., 5 min) was added to G. lamblia growth medium.GDC: glycodesoxycholate, GCDC: glycochenodesoxycholate, TDC:taurodesoxycholate, TCDC: taurochenodesoxycholate.

FIGS. 7A to 7D: Measurement of G. lamblia inhibition by flow cytometry.

FIG. 8: Percentage of living G. lamblia parasites when cultivated in thepresence of varying Lactobacillus strains.

FIG. 9: Enzymatic activity of recombinant BSH-47 produced in E. coli. E.coli wild type or E. coli secreting BSH-47 were incubated in thepresence of taurodeoxycholic acid 0.3% (upper panels) or in the presenceof glycodeoxycholic acid 0.3% (lower panels).

FIG. 10: Histogram representing the number of living Giardia parasites(in cells per ml) after incubation with (from left to right) medium,medium and bile, C. perfringens BSH (1 U), C. perfringens and bile,recombinant BSH-47, recombinant BSH-47 and bile.

FIGS. 11A and 11B: Inhibition of Giardia lamblia growth by enzymaticallyactive recombinant BSH from LjLA1 in the presence of bovine bile (0.6g/L) after 20 h of incubation. FIG. 11A represents the inhibition of G.lamblia growth by recombinant BSH-47. FIG. 11B represents the inhibitionof G. lamblia growth by recombinant BSH-56.

FIGS. 12A and 12B: G. lamblia cysts or trophozoites counts afteradministration to animals. Newborn mice received either PBS, LjLa1 or L.gasseri CNCM 1-4884 by intragastric gavage (5.10⁸ CFU/mice) daily fromday 5 before inoculation with the trophozoites of G. lamblia WB clone C6(10⁵ trophozoites per animal). Gavages were performed until day 15 (n=8to 12/group). FIG. 12A: Giardia trophozoites count in the smallintestine. Values are mean±SEM; p<0.05. FIG. 12B: Giardia cysts countsin large intestine of mice belonging to different groups. Values aremean±SEM; p<0.05.

FIG. 13: G. lamblia trophozoites count in the small intestine. Mice werechallenged with the trophozoites of G. lamblia WB clone C6 (10⁵trophozoites per animal) at day 10 Animals were treated either with PBSor BSH-47 at 1 μg/ml (0.5 μg per mice), 10 μg/ml (5 μg per mice) or 100μg/ml (50 μg/mice) by daily intragastric gavage until day 15 (n=10 to11/group). Values are mean±SEM; p<0.05.

EXAMPLES Example 1: Material and Methods Products and Preparation ofStock Solutions

Bovine bile solutions (Sigma and Difco) were prepared at 100 mg/ml stocksolution in distilled water, filtered at 0.2 μm and stored at −20° C.Pure bile salts (Sigma): glycocholate (GC), taurocholate (TC),glycodeoxycholate (GDC), taurodeoxycholate (TDC), glycochenodeoxycholate(GCDC) and taurochenodeoxycholate (TCDC), bile salt mix (Sigma) or purecorresponding bile salts (Sigma): cholate (C), deoxycholate (DC) andchenodeoxycholate (CDC), and fusidic acid (Sigma) were dissolved indistilled water to 12 mg/ml stock solution, filtered at 0.2 μm and keptat −20° C. Choloylglycine Bile Acid Hydrolase (or Bile Salt Hydrolase,BSH, EC 3.5.1.24) from Clostridium perfringens (Sigma) was prepared at10 U/ml in distilled water (milli-Q grade) and stored at −20° C.Iodoacetic acid (Sigma) was prepared as 0.5 M stock solution indistilled water and frozen at −20° C. Fetal calf serum was from PAALaboratories, GE Healthcare. The NEFA-C kit used for quantitativedetermination of non-esterified fatty acids (NEFAs) was from Biolabo(WAKO Diagnostics).

Cell Culture of Giardia lamblia

Trophozoites of G. lamblia strains WB (clone C6, ATCC30957) and HP1(Portland-1, gift of J. Tackezy) were grown as previously described inTYI-S-33 Keiser's medium (KM) with some modifications. TYI-S-33 wasadjusted at pH 6.0, supplemented with 10% heat-inactivated fetal calfserum (Paget et al., 2004) and 0.6 mg/ml bovine bile (Carnaby et al.,1994). They were regularly subcultured at a density of 5×10⁴ cells pertube (12 ml) from log phase parasites chilled on ice for 10 min andcentrifuged at 700×g, 5 min.

Culture of Lactobacillus johnsonii and Production of BacterialSupernatant

L. johnsonii La1 (LjLa1), CNRZ 1897, NCC533, was kindly provided byPascal Quénée (INRA Jouy en Josas, Equipe Atalis) and has been isolatedfrom LC1 product in 1996 (Chambourcy, France). LjLa1 stock cultures werekept frozen in MRS Broth media with 15% glycerol. Bacteria weresubcultured in MRS Broth medium (Sigma) or modified TYI-S-33 medium(MTYI) (Perez et al. 2001) and incubated anaerobically for 12-18 h at37° C. Bacteria were subsequently grown in MTYI or KM mediumsupplemented or not with 10% heat-inactivated fetal calf serum for 12-16h in the presence or absence of 0.6 mg/ml bovine bile. Aftercentrifugation (3,000×g, 10 min) and 0.2 μm filtration, the pH of thebacterial supernatant was adjusted to 6.0, 6.2, 6.7, 6.9 or 7.2 with 5 NNaOH. Appropriated controls were prepared as follows: lactic acidproduced during growth was quantified from aliquots of supernatants(Enzytec™ kit, R-Biopharm) and equivalent amount of lactic acid wasadded to fresh medium before pH adjustment.

In Vitro G. lamblia Growth Inhibition Assay

One milliliter of trophozoites suspension (1×10⁵ parasites/ml in KMsupplemented with 10% fetal calf serum but without bovine bile) wasmixed with either 500 μl of bacterial supernatant or bile salt hydrolasefrom C perfringens (BSH, 0.2, 1 or 2 U) or appropriate controls in KM orMTYI, in the presence of different concentrations of either bovine bile(0 to 0.6 mg/ml), mixed bile salts (0 to 0.2 mg/ml), conjugated bilesalts (0 to 0.2 mg/ml) or deconjugated bile salts (0 to 0.2 mg/ml).Samples were incubated for 24 h at 37° C. and then chilled on ice for 10min to dislodge trophozoites from tube wall. Living trophozoites(parasites with pear shape showing signs of flagella mobility) werecounted using Malassez cell chamber and/or using an hemocytometer.Multiplication factor (i.e. number of total trophozoites at the end ofthe experiment/number of trophozoites at time zero), survival rate (i.e.(number of living cells/total number of trophozoites)×100) andinhibition percentage (i.e., 100-(number of living cells in the presenceof tested compounds/number of living cells in control)×100) werecalculated.

Partial Purification of Active Fractions from Bacterial Supernatants byGel Filtration

Supernatants from LjLa1 cultures in MTYI or KM, adjusted to pH 6.0, wereconcentrated up to 30-fold by ultrafiltration using 10 kDa Centriprepcentrifugal filter unit (Millipore). After 0.2 μm filtration, theconcentrated supernatants were placed on a Sephacryl S300 column 16/100(GE Healthcare) previously equilibrated with 20 mM ammonium sulfate, pH6.0, in a cold room and were eluted with the same buffer at a flow rateof 1.8 to 2.0 ml/min. Twelve effluent fractions of 12 ml were obtained,concentrated 4-fold by ultrafiltration on a 10 kDa Centriprep asdescribed above, and tested for Giardia inhibition by classical in vitrogrowth inhibition assays in the presence of bovine bile or bile salts.Fractions obtained by similar processing of elution buffer alone andcontrol media containing lactic acid (see above) were used as controls.Column calibration was carried out with ribonuclease A (13,700 Da) andbovine serum albumin (67,000 Da).

Characterization of the Active Molecule(s) in LjLa1 Supernatant

Molecular size of active molecule(s) present in the bacterialsupernatant was assessed by ultrafiltration using 10 kDa, 30 kDa and 50kDa Centriprep centrifugal filter units. Thermal stability was tested byheating bacterial supernatant at 90° C. for 10 minutes. Preservation ofthe LjLa1 supernatant activity upon dialysis was checked by dialyzingtwice (for 2 h and 15 h at 4° C., respectively) the supernatant against100 volumes of KM medium supplemented with 10% FCS or against GKNsolution (Pérez et al., 2001) (NaCl, 8 g/l; KCl, 0.4 g/l; glucose, 2g/l; NaH₂PO₄, H₂O, 0.69 g/l; Na₂HPO₄, 1.57 g/l; pH 7.2 to 7.4) using aMWCO 3.5 kDa Spectra-Por dialysis membrane. The dialyzed supernatant wasthen sterilized by filtration through 0.2 μm membrane and kept frozen at−80° C. before G. lamblia inhibition assays.

Finally, biochemical nature of active molecules was determined bypreincubating 5-fold concentrated bacterial supernatant obtained byultrafiltration (>10 kDa) with different proteases coupled to beads.Briefly, proteinase K (Invitrogen) and pronase (Merck) were coupled toCNBr-activated Sepharose™ 4B (GE Healthcare) following manufacturer'sinstructions. Five milliliter of 5-fold concentrated bacterialsupernatant or 5-fold concentrated fresh control medium were incubatedfor 6 h at room temperature in presence of 100 μl of packed beadspreviously coupled with 1 mg of each protease. Before growth inhibitionassays, beads were removed by centrifugation (4,000×g 5 min). To assessproteases ability to digest proteins from bacterial supernatant, proteincontent before and after incubation with proteases, was estimated bySDS-PAGE after trichloroacetic acid (TCA) precipitation.

Measurement of Free Fatty Acids

To assess the presence of free fatty acids in the complex mediuminducing Giardia growth inhibition, FCS, bile and LjLa1 supernatant(LjLa1sn) were analyzed for non-esterified fatty acids (NEFAs) contenteither alone (FCS, LjLa1sn, bile) or in combination (FCS-bile,FCS-LjLa1sn, bile-LjLa1sn, FCS-bile-LjLa1sn). Concentration of eachcomponent was that in the inhibition assay. Samples (0.5 ml) wereprepared and kept on ice before being incubated for 24 h at 37° C. inthe presence of 4.8×10⁴ trophozoites or without cells. At the end of theincubation period, tubes were chilled on ice, centrifuged at 700×g, 10min at room temperature, then the supernatant was taken and frozen at−80° C. before NEFAs measurement. Numbers of living and deadtrophozoites were determined using a Malassez cell chamber. NEFAs werequantified by using the NEFA-C kit, following manufacturer'sinstructions. Oleic acid was used as standard and NEFAs were expressedas oleic acid equivalents (Eq).

Bile Salt Hydrolase Activity Assays

After gel filtration, the eluted fractions were concentrated 10-fold bydialysis against 20 mM ammonium acetate buffer containing 2 M sucrose,pH 6.0, using a 3.5 kDa MWCO membrane (Spectrum Laboratories).Glycodeoxycholate (GDC) was used to perform growth inhibition assays andenzymatic assays. BSH activity was monitored by measuring glycineliberation from conjugated bile salt, following the protocol describedby Grill et al., (2000). Briefly 100 μl of effluent fractions or BSH 1unit or elution buffer were mixed with 100 μl of 2.4 g/l of GDC andincubated 24 h at 37° C. Controls were performed in the absence of bilesalt or by pre-incubating effluent fractions with 2 mM iodoacetic acidor 30 min at 37° C. To stop the enzymatic reaction, an equal volume of15% TCA (200 μl) was added and proteins were precipitated bycentrifugation at 20,000 g for 15 minutes. 680 μl of 0.3 M boratebuffer, 1% SDS, pH 9.5 and 80 μl of 0.3% picrylsulfonic acid solution(Sigma) were added to 80 μl of supernatants. Mixtures were incubated for30 min in the dark and 800 μl of 1 mM HCl were added to stop thereaction. Glycine concentration was measured at 416 nm using an Uvikonspectrophotometer 930 (Kontron Instruments). Standard curve wasestablished with free glycine.

LC/ESI-MS Analysis of Modifications of Bile Components by LjLa1Supernatants

125 μl of bile-containing culture media of G. lamblia (KM, pH 6.0, with2 g/L bovine bile) and 125 μl of LjLa1 supernatants prepared from abacterial culture in KM medium supplemented with 10% fetal bovine serum,adjusted at pH 6.0 were mixed and incubated overnight at 37° C. Twodifferent bile batches (B1 and B2) and two different bacterialsupernatants (S1 and S2) were tested. The samples were diluted 4-fold inMilli-Q water and subjected to solid-phase extraction (SPE) using Oasis®HLB cartridges (30 mg solid phase). After conditioning with 3 mlmethanol and 3 ml Milli-Q water, the cartridges were loaded with 1 ml of4-fold diluted sample, washed with 2 ml Milli-Q water and eluted with 2ml methanol. The eluted fractions were dried under vacuum andresuspended in 500 μl Milli-Q water/acetonitrile 90:10 (v/v). Five μl ofeach resuspended sample was analyzed by LC/ESI-MS on a Ultimate U3000chromatographic system (Thermo) connected to a Q-STAR Pulsar Qq-TOF massspectrometer equipped with an ionspray source (AB Sciex). The LCseparation was achieved on a Interchrom Strategy C18-2 micro column (5μm, 150×1 mm, 100 Å, Interchim). The elution gradient was 10% mobilephase B (acetonitrile) to 70% B against mobile phase A (5 mM ammoniumformate/formic acid, pH 6) over 45 min, at a flow rate of 40 μl/min. TheMS data were acquired in negative mode, in the range m/z 250-1200. EachLC/ESI-MS experiment was conducted twice. Data-dependent LC/ESI-MS/MSexperiments were also conducted on each sample, alternating 1-secondfull-scan MS followed by two 2-second product ion collision induceddissociation (CID) of the major ions detected at the first step, using a−50 V collision voltage. Each raw LC/ESI-MS data was converted intoNetwork Commun Data Form (NetCDF) using the translation tool provided byAB Sciex. The data were processed with XCMS (Smith et al. 2006), asoftware implemented in the freely available R environment(www.r-project.org), which allows automatic retention time alignment,matched filtration, peak detection and peak matching.

Protein Precipitation

0.1% of sodium lauroyl sarcosinate (NLS, Sigma) was added to bacterialsupernatants. After mixing, TCA (trichloroacetic acid) was added to afinal 7.5% concentration, and the solution was precipitated on iceovernight. The mixed protein-detergent precipitate was collected bycentrifugation (10,000×g, 10 min, 4° C.). The supernatant was carefullyremoved and the pellet washed twice with 2 ml of precooledtetrahydrofuran (Sigma). Finally, the pellet was dissolved in 0.4 mlextraction solution (7 M Urea, 2 M Thiourea, 4% CHAPS, 5 mMTris(carboxyethyl)phosphine) (Rabilloud et al., 2009).

Proteomic Analysis of LjLa1 Supernatant

TCA precipitated LjLa1 supernatant was resuspended in 8 M urea in 20 mMTEAB (triethylammonium bicarbonate) and incubated for 1 h at roomtemperature (RT) with 20 mM DTT (Dithiothreitol), then with 50 mM IAA(iodacetamide) and incubated for a further hour at RT in the dark. Thesample was incubated with 0.05 UA of endoproteinase Lys-C (Wako PureChemical Industries, Osaka, Japan) for 18 h at RT. Trypsin (Promega)digestion was performed with 2 μg of enzyme during 4 h at RT andterminated with TFA (trifluoroacetic acid), final concentration of 0.5%.The sample was passed sequentially through two home-made Poros Oligo-R3(PerSeptive Biosystems, Framingham, USA) microcolumns packed (±1 cm) onp200 tips over 3 MM C18 material plug. Loaded resin was washed with 100μl 0.1% TFA and peptides were eluted with 100 μl 70% acetonitrile(ACN)/0.1% TFA, then 20 μl 100% ACN. The sample was desalted, drieddown, resuspended in 50% ACN and 10% was collected to amino acidanalysis using a Biochrom 30 amino acid analyzer (Biochrom, Cambridge,U.K.), then dried and stored at −80° C. again until analysis.

Samples (3 μg per run) were analyzed by an EASY-nano LC system (ProxeonBiosystems, Odense, Denmark) coupled online to an LTQ-Orbitrap Velosmass spectrometer (Thermo Scientific, Waltham, USA). Peptides wereloaded onto a 18 cm fused silica emitter 75 μm inner diameter) packedin-house with reverse phase capillary column ReproSil-Pur C18-AQ 3 μmresin (Dr. Maisch GmbH, Germany) and eluted using a gradient from 100%phase A (0.1% formic acid) to 35% phase B (0.1% formic acid, 95%acetonitrile) for 180 min, 35% to 100% phase B for 5 min and 100% phaseB for 8 min (a total of 23 min at 250 nl/min). After each run, thecolumn was washed with 90% phase Band re-equilibrated with phase A. Massspectra were acquired in positive mode applying data-dependent automaticsurvey MS scan and tandem mass spectra (MS/MS) acquisition. Each MS scanin the orbitrap (mass range of m/z of 400-1800 and resolution 100,000)was followed by MS/MS of the fifteen most intense ions in the LTQ.Fragmentation in the LTQ was performed by collision-induced dissociationand selected sequenced ions were dynamically excluded for 25 s. Raw datawere viewed in Xcalibur v.2.1 (Thermo Scientific, Waltham, USA) and dataprocessing was performed using Proteome Discoverer v.1.3 (ThermoScientific, Waltham, USA). Generated raw files were submitted tosearching using Proteome Discoverer with an in house Mascot v.2.3algorithm against database of proteins predicted from the L. johnsoniiisolates NCC533 and FI9785 and the L. johnsonii prophage Lj965.Contaminant proteins (several types of human keratins, BSA and porcinetrypsin) were also added to the database and all contaminant proteinsidentified were manually removed from the result lists. The searcheswere performed with the following parameters: ms accuracy 10 ppm, MS/MSaccuracy 0.6 Da, trypsin digestion with one missed cleavage allowed,fixed carbamidomethyl modification of cysteine and variable modificationof oxidized methionine and N-terminal protein acetylation. Number ofproteins, protein groups and number of peptides were filtered for FalseDiscovery Rates (FDR) less than 1% and only peptides with rank 1 andminimal of 2 peptides per proteins were accepted for identificationusing Proteome Discoverer (Charneau et al., 2007); Queiroz et al. 2013).

Example 2: L. johnsonii La1 Supernatant Inhibitory Effect is DependentUpon Bovine Bile and More Specifically Upon Bile Salts

Most media previously described to support G. lamblia growth commonlycontains bile as a supply for parasite cholesterol and fatty acidsrequirements (Farthing et al., 1985, Gillin et al., 1986, Halliday etal., 1995).

In our hands, G. lamblia trophozoites growth can be observed in a commonmedium (KM-FCS) in the absence of bovine bile. Moreover, recommendedbile concentrations (0.75 mg/ml, Perez et al., 2001) appeared to affecttrophozoites growth when added to the common KM-FCS (FIG. 1A).Interestingly, LjLa1 inhibitory effect was observed only in presence ofbile. No inhibitory effect by the supernatant could be observed in theabsence of bovine bile, even after 24 h of culture (FIG. 1A). Inpresence of 0.75 g/L of bovine bile (Perez et al., 2001), G. lambliatrophozoites growth was slightly impacted by bacterial supernatant after10 hours of contact but largely affected after 24 hours of contact(9.10⁴ and 1.10⁴ trophozoite/ml, respectively, FIG. 1A). Thus, the 24 hincubation time-period was retained for all subsequent inhibitory growthassays.

Maximum inhibitory effects of LjLa1 supernatant on parasite growth wasobserved either in the presence of 0.6 g/L complete bovine bile or inthe presence of 0.032 g/L bile salts (96.3% and 75% of inhibition,respectively, by comparison with controls containing similar amount oflactic acid and bile or bile salts, FIG. 1B). Similar effects wereobserved using two isolates of G. lamblia (WB and HP1), two differentcommercial origins of bovine bile and two different media compatiblewith bacteria and parasite growth: MTYI (Perez et al., 2001) and KM-10%FCS (Data not shown). Subsequent inhibition in vitro assays were thusperformed using 0.6 g/L of bovine bile.

Example 3: Characterization of the Inhibitory Activity

To biochemically characterize the inhibitory compounds present in theLjLa1 supernatant, this supernatant was treated with immobilized enzymesprior to contact with parasites. Parasite growth inhibition wasabolished by proteinase K and pronase treatments of the supernatant,suggesting involvement of inhibitory factor(s) of peptidic nature (FIG.2A). Heat-treatment also led to inactivation of the inhibitoryproperties of the bacterial supernatant (FIG. 2A). Additionally, in a pHrange similar to the ones experienced by G. lamblia in vivo (Biagini etal., 2001), a strong influence of pH on the inhibitory reaction wasnoticed, with highest inhibition occurring at pH 6.2 (FIG. 2B).

Moreover, as Pridmore et al. (2004) demonstrated that the LjLa1anti-Salmonella activity is mediated by the toxic hydrogen peroxidemolecule H₂O₂ and can be abolished by a pretreatment with catalase, wechecked whether treatment of LjLa1 supernatant with catalase mightprevent its anti-Giardia effect. As it can be seen in FIG. 2A, catalasepretreatment only slightly affected the inhibitory activity of the LjLa1supernatant on G. lamblia (FIG. 2A), invalidating the role of H₂O₂ inGiardia growth inhibition.

Example 4: Giardia Growth Inhibition by LjLa1 Supernatant is not Clue toFree Fatty Acids

To assess whether G. lamblia growth inhibition by LjLa1 supernatantmight be due to toxic free fatty acids as demonstrated in previousreports (Rohrer et al. 1986), FCS, bile and LjLa1 supernatant wereanalyzed for non-esterified fatty acids (NEFAs) content either alone orin combination, using the NEFA-C methodology (WAKO diagnostics). Thedifferent samples were incubated for 24 h at 37° C. with or without G.lamblia trophozoites and the cell supernatants were analyzed for NEFAs.Survival and growth of the parasites in those different conditions weredetermined.

The following Table 1 represents the analysis of non-esterified fattyacids involvement in Giardia inhibition. The different components of theGiardia culture medium (FCS 10% and/or bile 0.5 g/L), as well asLjLa1sn, were analyzed either alone or in combination for NEFA contentafter 24 h of incubation at 37° C. Incubation was performed with orwithout G. lamblia trophozoites (9.6×10⁴/ml). Survival andmultiplication of G. lamblia after 24 h in those different media weredetermined. Parasite multiplication was expressed as the number of totaltrophozoites after 24 h of incubation/number of trophozoites at timezero of incubation (i.e. multiplication factor). Trophozoite survivalrate after 24 h of incubation was expressed as the (number of livingcells/total number of cells)×100.±SD (triplicate).

Supernatants with FCS, LjLa1sn or bile alone displayed NEFAsconcentrations of 40.9, 36.3 and 4.5 μM, respectively (Table 1).

TABLE 1 NEFAs Multiplication Survival Incubation medium (μM Eq) factorrate (%) KM 0 1.1 14.3 KM + FCS 40.9 3.3 89.8 KM + bile 4.5 0.7 0  KM +LjLa1sn 36.4 1.2 71.6 KM + FCS + bile 95.4 2.3 93.8 KM + FCS + LjLa1sn68.2 2.1 87.5 KM + bile + LjLa1sn 50.0 0.8 0  KM + FCS + bile + LjLa1sn140.9 0.8 0 

The amount of NEFAs was doubled (95.4 μM) by co-incubation of the bilewith serum suggesting enzymatic release of NEFAs. However, equal amountswere found at time zero and time 24 h of the co-incubation (not shown),indicating that fatty acids were not released in a time-dependentmanner. It was hypothesized that the high amount of NEFAs might resultfrom a detergent-like action of the bile on serum lipids, possiblyimproving accessibility of NEFAs to the NEFA-C kit reagents. The highestamount of NEFAs (140.9 μM) was measured upon co incubation of FCS withbile and LjLa1sn, as could be expected by summing their respective NEFAscontents. Incubation with G. lamblia had no noticeable effect on theNEFA content of the various samples (Data not shown).

Normal growth of G. lamblia (multiplication factor: 3.34, Table 1) wasobserved in the presence of 10% FCS alone. Trophozoites did not survivein KM medium containing only bile, whereas most of them (˜70%) werestill alive although they did not develop when incubated in KM withLjLa1 supernatant, most probably due to the low concentration of FCS inLjLa1 supernatant. Remarkably, trophozoites survival was abolished uponaddition of bile to LjLa1 sn although the same concentration of FCS ispresent, indicating the presence of inhibitory elements. By comparingNEFAs contents of the different media, it appeared that NEFAs couldhardly be responsible for parasite death. Indeed, more NEFAs were foundin the KM+FCS+bile or KM+FCS+LjLa1sn media (95.4 and 68.2 μM of NEFAsrespectively), which allowed parasite survival, than in theKM+bile+LjLa1sn medium (50.0 μM of NEFAs) which induced the death of allthe parasites. This indicated that the concomitant addition of bile andbacterial supernatant rather than high level of NEFAs is lethal toGiardia and is responsible for the killing effect observed in thepresence of FCS, bile and LjLa1 supernatant.

Example 5: Characterization of LjLa1 Supernatant Inhibitory Activity TheLjLa1 Supernatant Inhibitory Activity is Due to −30 kDa Molar MassFactor(s)

Fractionation experiments indicated that the inhibitory activity inLjLa1 supernatant was due to molecule(s) bigger than 10 kDa, sincefraction >10 showed a high G. lamblia inhibitory activity compared tothe fraction <10 kDa (FIG. 2C). By performing a 30 kDa thresholdfractionation, we found that the inhibitory activity concentrated mostlyin the >30 kDa fraction (inducing 66% of Giardia growth inhibition, FIG.2C), however moderate inhibitory effect (˜40%) was also observed withthe <30 kDa fraction, which led us to propose that the molar mass(es) ofthe active molecule(s) are close to this threshold. In good accordancewith this, 50 kDa threshold fractionation of the LjLa1sn was unable tosegregate the inhibitory activity, i.e. 50% and 48% of Giardia growthinhibition were induced by the <50 kDa and >50 kDa fractions,respectively (FIG. 2C), indicating that inhibitory protein(s) molar massis smaller than 50 kDa.

Small Compounds are not Primarily Involved in LjLa1sn InhibitoryActivity

It has been reported that molecule(s) smaller than 1 kDa (Perez et al.,2001) would be involved in the giardiacidal activity of the LjLa1supernatant, in contradiction with our findings of a ≥30 kDamolecule(s). The possibility that dialysis against GKN buffer as used inPerez's report might somehow inhibit the activity has been checked.Several points were checked. At first, because the pH of the GKN bufferis 7.4 and the LjLa1sn inhibitory activity is inactivated at pH above7.0 (FIG. 2B), pH of the KM medium was checked after supplementationwith 10% FCS and 25% GKN. The pH was found to be increased to 6.5, hencenot expected to inactivate LjLa1 supernatant (FIG. 2B). Second, toassess whether small component(s) might be involved in the inhibitoryeffect, the bacterial supernatant was dialyzed using a 3.5 kDa molecularweight cut-off membrane against both KM 10% FCS and GKN buffer. As canbe seen in the following Table 2, parasite killing activity of the LjLa1supernatant in the presence of bile was fully recovered after dialysis,whatever the dialysis solution. Table 2 represents dialysis through lowMW cutoff membrane does not inactivate inhibitory activity of LjLa1supernatant (LjLa1sn). KM-FCS medium, bile (0.5 g/L) and LjLa1sn, eitheralone or in combination, were dialyzed against GKN buffer or KM-FCS, andthen tested for G. lamblia trophozoites growth. Values are mean of twoindependent experiments performed in duplicate.

TABLE 2 KM + KM + KM + FCS + KM + FCS + KM + FCS + FCS FCS + LjLa1snLjLa1sn LjLa1sn GKN dialysed dialysed against against KM-FCS GKNMultiplication factor 3.82 2.60 3.24 3.68 2.44 Survival rate (%) 93.792.3 88.3 90.2 89.3 KM + KM + FCS + KM + FCS + KM + FCS + FCS + bile +bile + LjLa1sn bile + LjLa1sn bile LjLa1sn dialysed dialysed againstagainst KM-FCS GKN Multiplication factor 2.28 1.16 1.46 0.8 Survivalrate (%) 92.9 0 0 0

This indicates on one side that no element crucial to activity is lostupon dialysis and on the other side that the GKN buffer is notinhibitory to the LjLa1 supernatant activity. Also, it can be noticedfrom Table 2 that addition of 25% GKN buffer to KM-FCS does not affectparasite survival but slows down its development (multiplication rate of2.60 in the presence of GKN versus 3.82 in the absence of GKN).

Example 6: Impact of LjLa1 Supernatant on Bile Composition

Since concomitant addition of bile and LjLa1sn to the culture mediumleads to inhibition of G. lamblia growth, we assessed whether bilecomposition might be modified by LjLa1 supernatant. Bile compositionafter 24 h of incubation with LjLa1sn was investigated by massspectrometry (FIGS. 3A-B). Impacted molecules were identified by theirMS/MS fragmentation pattern. Comparison of bile salts profiles showed adecrease of conjugated salts (GC, TC, GDC, TDC, GCDC, TCDC) in favor ofnon-conjugated salts. Cholate and desoxycholate were the mainlystatistically enhanced non-conjugated salts when bile was incubated withLjLa1 supernatant (FIG. 4) and in a minor proportion chenodesoxycholate.These modifications were not observed in presence of heat-treatedbacterial supernatant (FIG. 3C).

Example 7: Impact of Deconjugated Bile Salts on G. lamblia TrophozoitesGrowth

The inhibitory effects toward G. lamblia growth of pure bile salts(cholate, desoxycholate and chenodesoxycholate) conjugated to glycine ortaurine, or their deconjugated counterparts were investigated in thepresence or the absence of LjLa1 supernatant (Table 3, FIG. 5). In theabsence of LjLa1sn, glycyl- or tauryl-conjugated salts as well asdeconjugated cholate showed no apparent toxicity at the concentrationstested (IC₅₀ values >500 μM). In contrast, the deconjugated salts DC andCDC exhibited inhibitory effects on trophozoites growth with IC₅₀ valuesof 132 μM (DC) and 147 μM (CDC) respectively. Interestingly, in thepresence of LjLa1 supernatant, the conjugated bile salts IC₅₀ valuesfelt to a range of values similar to those measured for their puredeconjugated counterparts, i.e. 104 μM (GDC), 79 μM (TDC), 110 μM (GCDC)and 115 μM (TCDC) (Table 3 and FIG. 5).

The following table 3 shows conjugated bile salts in association withLjLa1 supernatant (LjLa1sn) as well as deconjugated bile salts preventthe growth of G. lamblia. Various concentrations of taurine- andglycine-conjugated and unconjugated C, DC and CDC bile salts were testedfor G. lamblia trophozoites growth inhibition in KM-FCS in the presenceor absence of LjLa1sn (bacterial spent culture medium). IC50 values weredetermined from drug-response curves and expressed as mean+/−SD of atleast three independent experiments.

TABLE 3 With culture medium With bacterial spent only culture mediumIC50 +/− SD (μM) IC50 +/− SD (μM) C and C Cholate >400 >400 derivativesGC Glycocholate >400 >400 TC Taurocholate >400 >400 DC and DCDesoxycholate 132 +/−12,7 117 +/− 12,7 derivatives GDCGlycodesoxycholate >400 104 +/− 12,7 TDC Taurodesoxycholate >400  79 +/−17,3 CDC and CDC Chenodesoxycholate 147 +/−14,5 118 +/− 21,7 derivativesGCDC Glycochenodesoxycholate >400 110 +/− 10,6 TCDCTaurochenodesoxycholate >400 115 +/− 7,7  FA Fusidic acid 26 +/−3,7 nd

These results suggested that a deconjugating process mediated by LjLa1sn component(s) and producing deconjugated bile salts might beresponsible for the inhibitory effect of the association of bile andLjLa1sn. Such hypothesis is in line with the previous observation thatfusidic acid, an antibiotic with a bile salt-like chemical structure istoxic to Giardia (see Table 3, IC₅₀ value=26 μM) unless conjugated totaurine or glycine (Farthing et al., 1986).

Example 8: Potential Involvement of L. johnsonii La1 Bile-SaltHydrolase(s) in Bile-Mediated Giardia Inhibition, and Co-Elution ofBSH-Like Activity and Giardia Inhibitory Activity in Size FractionationChromatography of LjLa1 Supernatant

It is known that bile salt deconjugating process is mediated by 3-alpha,7-alpha, 12-alpha-trihydroxy-5-beta-cholan-24-oylglycine/taurineamidohydrolases (EC 3.5.1.24), also named choloylglycine/taurinehydrolases or conjugated bile acid hydrolases (CBAH) or bile salthydrolases (BSH). These enzymes act on carbon-nitrogen bonds other thanpeptide bonds, specifically in linear amides, releasing glycine andtaurine from conjugated bile salts. In L. johnsonii genome, three genesencoding BSH-like enzymes have been predicted (LJ0056 (BSH-56), LJ1147(BSH-47) and LJ1412 (BSH-12) genes). They are also predicted as secretedproteins by SecretomeP, with theoretical full sizes of 34.9 kDa, 36.3kDa and 36.6 kDa and secreted sizes of 29.8 kDa, 31.0 kDa and 31.3 kDa(data not shown).

To test the hypothesis of bacterial BSH(s) involvement in G. lambliagrowth inhibitory activity by LjLa1sn, the bacterial supernatant wasfractionated by gel filtration chromatography on Sephacryl S300 column16/100, and eluted fractions were assayed for parasite inhibition andbile salt deconjugating activity.

A typical elution profile is shown in FIG. 5A. Twelve eluated fractions(FIG. 5A) were tested for G. lambia growth inhibition (FIG. 5C) and themost active ones were further tested for BSH-like activity (FIG. 5B).Greatest inhibitory activity was recovered from fractions containingproteins with molecular weight between 13.7 kDa and 67 kDa (FIG. 5A).Those fractions exhibited BSH-like activity (FIG. 5C), as measured bythe release of glycine from GDCA. In our experimental conditions, 1 unitof the commercial Clostridium perfringens BSH induced the release of0.76 mM glycine from 2.5 mM GDC within 24 hours. Concomitant elution ofinhibitory and BSH activities within similar molecular weight range wasobserved with LjLa1 supernatants from different culture batches. Ourattempts to further purify elements responsible for inhibitory activityand/or BSH-like activity by combining steps of ion-exchangechromatography, hydrophobic interaction chromatography andchromatofocusing were unsuccessful, with a rapid loss of the activities.

Example 9: Deconjugation of Tauryl- and Glycyl-DC and -CDC byClostridium perfringens BSH is Toxic to G. lamblia

To assess capability of BSH enzymes to promote bile-mediatedanti-Giardia effect, BSH from the bacteria C. perfringens was tested forG. lamblia growth inhibition in the presence of bile or pure conjugatedbile salts. As noted above (Table 3), the glycine or taurine conjugatedbile salts, TDC, TCDC, GDC and GCDC have no inhibitory activity on G.lamblia growth in KM-FCS culture medium. In contrast, the addition of 2units of C. perfringens BSH to the culture in the presence of those bilesalts led to a remarkable parasite growth inhibition within the 24 h ofthe assay, with inhibition ranges of 95 to 100%, depending upon theconjugated bile salt tested (FIG. 6). Heat inactivation of bacterial BSH(100° C., 5 min) before its addition to the parasite culture led to adramatic fall of its anti-Giardia activity (less than 10% growthinhibition depending upon the conjugated bile salts tested, FIG. 6)indicating that BSH inhibitory activity depends on its enzymaticactivity.

Example 10: Mass Spectrometric Identification of Two BSH-Like Enzymes inthe LjLa1sn

It was then searched whether BSH-like enzymes annotated from L.johnsonii La1 genome, and predicted by SecretomeP to be secreted, areindeed released in the extracellular medium. High-resolution massspectrometry-based pro comic analysis of the LjLa1 extracellularproteins was performed. 3 μg of proteins of LjLa1 supernatants from twoindependent culture replicates allowed identification of over a hundredof secreted protein groups (data not shown). Amongst them, two of thethree predicted BSH were clearly identified in both replicates: LJ1412(gi|41583570) and LJ1147 (gi|41583360). The following Table 4 shows theidentification of two conjugated bile salt hydrolases of Lactobacillusjohnsonii NCC533 by MS/MS peptide fragmentation using MASCOT stringentsearch.

TABLE 4 peptide Theo. Accession Cov. unique totalPeptide ion sequence^(d) (with at ion Mass Theo number^(a) Score^(b) (%)^(c) peptides peptides PSMs least one peptide ion score >50)charge^(e) (m/z) (kDa)^(f) pI^(g) experimental replicate 1 gi|41583570162 12.58 2 2 5 NLANYSNIAPAQPK 2 750.9 36.6 5.2AHSPQGNNELSSVTNYFHILHSVEQPK 4 759.1 gi|41583360 39 12.92 3 3 3GLGIAGLNFTGPGK 2 651.4 36.3 4.9 DLPVTTLHWLMGDK 2 813.4 NTLVPNADINLYSR 2795.4 experimental replicate 2 gi|41583570  83 12.58 2 2 3NLANYSNIAPAQPK 2 750.9 36.6 5.2 AHSPQGNNELSSVTNYFHILHSVEQPK 4 759.1  gi|41583360  77  8.62 2 2 3 GLGIAGLNFTGPGK 2 651.4 36.3 4.9NTLVPNADINLYSR 2 795.4 ^(a)Accession number in the NCBI proteindatabase. All accession numbers refer to sequences from Lactobacillusjohnsonii NCC 533; ^(b)Probability based Mowse score of MASCOT softwarethat evaluates if the peptides subjected to search are the same as thosefound in the database originated by in silico digestion of a knownprotein; ^(c)Coverage is the percentage of predicted protein sequencecovered by matched peptides Via MASCOT; ^(d)Peptide sequences identifiedvia MASCOT following the experimental peptide masses after parental ionfragmentation. It was required that at least one spectrum should bematched with score of 50 or better to considered the hit. ^(e)Doubly- toquiraply-charged ions of selected peptides were analyzed.^(f)Theoretical molecular masses of proteins calculated from amino acidsequences; ^(g)Theoretical isoelectric points of proteins calculatedfrom amino acid sequences;

Example 11: Measurement of G. lamblia Inhibition by Flow Cytometry

The inhibitory effect of L. johnsonii on G. lamblia was measured by flowcytometry, as shown in FIGS. 7A to 7E. Propidium iodide, anintercalating agent fluorescing when excited at 540 nm, was used toevaluate Giardia cell viability in order to confirm Hemocytometerresults. These results showed that, tested separately, neither LjLa1snnor bovine bile (0.6 g/L) have cell lysis activity. However, in presenceof both Ljla1sn and bovine there is a fluorescence shift (FIG. 7E)evincing that bile has a cytotoxic effect on Giardia trophozoites (FIG.7D; FIG. 7E). Flow cytometry allowed us to analyse a higher amount ofcells and may be used routinely as a measurement method of G. lambliainhibition. Moreover, this technique has been used for otherlactobacilli supernatant (data not shown).

Example 12: Identification of Anti-Giardiasis Lactobacilli Strains

The inhibitory effect on G. lamblia growth of different lactobacillistrains was screened (cf. table 5). Bacterial supernatant wasco-incubated for 24 h at 37° C. with Giardia trophozoite cultures(triplicates), with or without bovine bile (0.6 g/L). Different speciesof lactobacilli were identified as potent inhibitors of Giardia lambliagrowth, as Lactobacillus johnsonii, Lactobacillus gasseri, Lactobacillusacidophilus, Lactobacillus reuteri. 14 lactobacilli strains showedsignificant inhibitory effects (ANOVA statistic tests) in presence ofbile (FIG. 8) None of the supernatant had an inhibitory effect withoutbovine bile, confirming that the giardiacidal effect is bile dependent.Table 5 indicates the corresponding internal and official references ofthe bacterial strains, and bibliographic references.

TABLE 5 Official reference Bacterial strain ATCC CIP (*) LMG (*) CNCM(*) Publication L. johnsonii I-4885 Fujisawa et al., 1992 L. gasseri33323 102991 9203 T Lauer and Kandler, 1980 L. johnsonii 103614 Fujisawaet al., 1992 L. johnsonii 103786 Fujisawa et al., 1992 L. johnsonii33200 103620 9436 T Fujisawa et al., 1992 L. johnsonii  332 103652 11468Fujisawa et al., 1992 L. johnsonii 11506 103653  9437 Fujisawa et al.,1992 L. johnsonii 103654 Fujisawa et al., 1992 L. johnsonii 103781Fujisawa et al., 1992 L. johnsonii 103782 Fujisawa et al., 1992 L.johnsonii Lal NCC533 Pridmore et al. (2004) L. gasseri 11413 L. gasseri29601 11414 I-4884 L. acidophilus N 700396  FM CIP (*): Collection del'Institut Pasteur, France LMG (*): Laboratorium voor Microbiologie,Gent University, Belgium CNCM (*): Collection Nationale deMicroorganismes, Institut Pasteur, France ATCC: American Type TissueCollection, USA

Example 13: Heterologous Expression of LjLa1 BSH in E. coli

To study the properties of the LjLa1 BSHs, we cloned the BSH genes intoa pStaby vector (StabyExpress, Delphigenetics) in order to purify BSHsusing His-Tag system. E. coli expressions cells (E. coli SE,Delphigenetics) were then transformed The recombinant BSH-47 protein wasproduced in E. coli SE cells and purified using a His-Tag system(Sephadex Ni-NTA column, GE Healthcare). The activity of recombinantBSH-47 was tested using taurodeoxycholic (0.3%) and glycodeoxycholic(0.3%) LB agar (Chae et al 2013). After 48 h of incubation at 37° C., weobserved that the recombinant BSH-47 is taurospecific (FIG. 9).Furthermore, the effect of recombinant LjLa1 BSH-47 has been studied onGiardia trophozoites cultures, in the presence or not of bovine bile(0.06 g/L). The results show that recombinant BSH-47 (0.96 U, with “U”designing enzymatic units) exhibits an inhibiting effect, the level ofthis inhibiting effect is equivalent to the inhibiting effect of C.perfringens BSH (1 U) (FIG. 10).

Example 14: Characterization of the Inhibitory Activity of LjLa1 BSH-47and BSH-56 In Vitro

The effects of recombinant LjLa1 BSH-47 and BSH-56 were studied oncultures of G. lamblia trophozoites in either presence or absence ofbovine bile (0.06 g/L). Recombinant BSH-56 was produced according to theprocess described for the production of BSH-47, such as described inExample 13. Several BSH concentration were tested ranging from 0, 0001μg/ml to 10 μg/ml. Interestingly, both BSH-47 (FIG. 11A) and BSH-56(FIG. 11B) exhibit strong inhibitory effects. These results are inagreement with those obtained with commercial C. perfringens BSH(Example 8) (FIG. 10). As expected, no inhibitory effect was observedwithout bovine bile.

Specific Activities:

Previous experiments allowed us to determine the substrate specificityof newly purified BSH-47 and BSH-56 and their specific activities hadbeen determined. BSH-47 is able to deconjugate taurospecific bile saltswhile BSH-56 is able to deconjugate both taurospecific and glycospecificbile salts.

TABLE 6 Specific activity (μmole of glycine/ Specific activity (μmoletaurine/ 5 min at 37° C. / mg of protein) 5 min at 37° C. / mg ofprotein) C. perfringens 0,690 0,150 BSH BSH-47 0,066 0,717 BSH-56 0,5362,604

Example 15: In Vivo Effect of L. Gasseri CNCM 1-4884 Against G. lamblia

L. johnsonii La1 and L. gasseri CNCM 1-4884 strains (L. gasseri CNCM1-4884 is also designated as L. gasseri ATCC29601 in FIG. 8 and in Table5) were daily administered by intragastric gavage (5×10⁸ CFU) toneonatal mice from day 5 to day 15 (day of sacrifice). Mice werechallenged with trophozoites at day 10 by intragastric gavage (1×10⁵trophozoites) and then were sacrificed at day 15. Preliminaryexperiments allow us to determine that there is a peak in the Giardiainfection rate 5 days postinoculation (data not shown). The presence ofliving trophozoites in the small intestine is a marker of Giardiainfection. Mice were divided into three groups with a minimum of 8animals per group. We observed a significant reduction (p<0.05) in theparasite load in the small intestine in groups treated with L. gasseriCNCM I-4884 compared to control animals administered with PBS (FIG.12A). Interestingly, L. gasseri CNCM 1-4884 was more efficient inreducing the number of trophozoites than L. johnsonii La1. In agreementwith these observations, the counting of cysts in the large intestineshowed a significant reduction (p<0.05) in groups treated with L.gasseri CNCM 1-4884 compared to controls, whereas no significantreduction was observed in the group treated with L. johnsonii La1 (FIG.12B).

Example 16: In Vivo Effect of BSH-47 Against G. lamblia

Solutions of recombinant BSH-47 solutions (1 μg/ml, 10 μg/ml and 100μg/ml diluted in NaHCO₃16.4%) were thawed and daily administered byintragastric gavage to neonatal mice (dose were respectively 0.05 μg,0.5 μg and 5 μg per mice) from day 10 to day 15 (day of sacrifice).Control animals received PBS instead of BSH. All groups treated withBSH-47 showed a reduction in trophozoites load in the small intestinecompared with the control (FIG. 13). However, only the group treatedwith 100 μg/ml of BSH-47 displayed significant reduction in the parasiteload.

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1-14. (canceled)
 15. A method of treating and/or reducing thedevelopment of giardiasis in a subject, comprising administering acomposition exhibiting a bile-salt hydrolase activity to a subject;wherein the composition is chosen from: a composition comprising atleast one bile-salt hydrolase (BSH) enzyme, wherein the BSH enzyme hasan amino acid sequence at least 95% identical to SEQ ID NO: 6; acomposition comprising a lactic acid bacterium able to secrete at leastone BSH enzyme, wherein the BSH enzyme has an amino acid sequence atleast 95% identical to SEQ ID NO: 6, and wherein the lactic acidbacterium is not Lactobacillus johnsonii La1, Lactobacillus acidophilus,Bifidobacterium bifidum or Bifidobacterium infantis; and a combinationthereof.
 16. The method of claim 15, wherein the administeredcomposition comprises at least one bile-salt hydrolase (BSH) enzymehaving an amino acid sequence at least 95% identical to SEQ ID NO: 6.17. The method of claim 16, wherein the BSH enzyme has the amino acidsequence of SEQ ID NO:
 6. 18. The method of claim 16, wherein thesubject is infected with Giardia.
 19. The method of claim 16, whereinthe subject is not infected with Giardia.
 20. The method of claim 16,wherein the subject is a human being or an animal.
 21. The method ofclaim 15, wherein the administered composition comprises a lactic acidbacterium able to secrete at least one BSH enzyme, wherein the BSHenzyme has an amino acid sequence at least 95% identical to SEQ ID NO:6, and wherein the lactic acid bacterium is not Lactobacillus johnsoniiLa1, Lactobacillus acidophilus, Bifidobacterium bifidum orBifidobacterium infantis.
 22. The method of claim 21, wherein the BSHenzyme has the amino acid sequence of SEQ ID NO:
 6. 23. The method ofclaim 21, wherein the subject is infected with Giardia.
 24. The methodof claim 21, wherein the subject is not infected with Giardia.
 25. Themethod of claim 21, wherein the subject is a human being or an animal.26. The method of claim 21, wherein the lactic acid bacterium able tosecrete at least one BSH enzyme is selected from: Lactobacillus, but notLactobacillus johnsonii La1 or Lactobacillus acidophilus; andBifidobacterium, but not Bifidobacterium bifidum or Bifidobacteriuminfantis.
 27. The method according to claim 26, wherein the lactic acidbacterium is a Lactobacillus chosen from the group consisting of:Lactobacillus johnsonii, but not Lactobacillus johnsonii La1;Lactobacillus gasseri; Lactobacillus acidophilus, but not Lactobacillusacidophilus La10; and Lactobacillus reuteri.
 28. A method of treating orreducing the development of giardiasis in a subject, comprisingadministering a composition exhibiting a bile-salt hydrolase activity toa subject; wherein said composition comprises a lactic acid bacteriumable to secrete at least one BSH enzyme, and wherein said lactic acidbacterium is not Lactobacillus johnsonii La1, Lactobacillus acidophilus,Bifidobacterium bifidum or Bifidobacterium infantis; wherein saidbile-salt hydrolase activity is determined by the detection of thepresence of glycine or taurine liberated from conjugated bile salts, ofcholic acid, of deoxycholic acid and/or of chenodeoxycholic acid. 29.The method of claim 28, wherein the subject is infected with Giardia.30. The method of claim 28, wherein the subject is not infected withGiardia.
 31. The method according to any claim 28, wherein said BSHenzyme comprises an amino acid sequence having at least 95% identitywith an amino acid sequence chosen from the group consisting of:Lactobacillus johnsonii La1 BSH-12 (SEQ ID NO: 1), Lactobacillusjohnsonii La1 BSH-47 (SEQ ID NO: 2), Lactobacillus johnsonii La1 BSH-56(SEQ ID NO: 3), Lactobacillus gasseri BSH-A (SEQ ID NO: 4),Lactobacillus gasseri BSH-B (SEQ ID NO: 5), Lactobacillus johnsonii DPC6026 BSH (SEQ ID NO: 6), Lactobacillus johnsonii DPC 6026 BSH (SEQ IDNO: 7), and Lactobacillus johnsonii DPC 6026 BSH (SEQ ID NO: 8).
 32. Themethod according to claim 28, wherein said administered compositioncomprises a lactic acid bacterium able to secrete a BSH, wherein saidbacterium is selected from: Lactobacillus, but not Lactobacillusjohnsonii La1 or Lactobacillus acidophilus; and Bifidobacterium, but notBifidobacterium bifidum or Bifidobacterium infantis.
 33. The methodaccording to claim 28, wherein said lactic acid bacterium is aLactobacillus chosen from the group consisting of: Lactobacillusjohnsonii, but not Lactobacillus johnsonii La1; Lactobacillus gasseri;and Lactobacillus acidophilus, but not Lactobacillus acidophilus La10;and Lactobacillus reuteri.
 34. The method according to claim 28, whereinthe subject is a human being or an animal.